PARIS: Defending Olympic champion Alexander Zverev kept cool in soaring temperatures to march into the third round of the men’s singles but women’s second seed Coco Gauff’s challenge wilted as she was knocked out in the third round on Tuesday.

Germany’s Zverev, the third seed, took to a sun-baked Court Philippe Chatrier after Gauff’s demise but avoided any similar mishaps as he beat Czech player Tomas Machac 6-3 7-5. American Gauff began superbly against experienced Croatian Donna Vekic but after failing to convert two set points in the opening set tiebreaker, slumped to a 7-6(7) 6-2 defeat.

Gauff was left in tears at a crucial juncture of the second set when an over-ruled line call saw her slip 4-2 behind, the American becoming embroiled on a lengthy argument with umpire Jaume Campistol and the tournament supervisor.

Vekic, the 13th seed, refused to let the incident affect her though and sealed a superb victory to become the first Croatian woman to reach the Olympic singles quarter-finals since 1996. “I felt that he called it before I hit and I don’t think the referee disagreed but he just thought it didn’t affect my swing, which I felt like it did,” Gauff, who is top seed in the women’s doubles and is also in the mixed doubles, told reporters.

“Afterwards they apologise, but ‘Sorry’ doesn’t help you once the match is over. But I’m not going to sit here and say one point affected the result. “I was already on the losing side of things.”

Zverev reached the French Open final this year and looked perfectly at home on the Parisian clay as he maintained a strong start to his bid to repeat his Tokyo gold. He was pushed hard in the second set as the heat took its toll but turned on the afterburners at 5-5 with two searing forehand passes earning him the crucial break of serve before he sealed the contest a game later.

With temperatures soaring into the mid 30s Celsius (90s Fahrenheit) at Roland Garros, organisers the International Tennis Federation invoked the extreme heat protocols that allowed for a 10-minute break after the second set of singles matches.

It came too late for Britain’s Jack Draper though, as he was beaten in the second round by American seventh seed Taylor Fritz despite edging a first-set on the tiebreak, afterwards saying he could not keep his water bottles cool.

“I’m a big sweater so to retain fluid was tough. It was pretty poor,” he said. “They give bottles to the players but the bottles don’t stay cool, so, you know, you’re drinking hot water out there. That’s not fun in those sort of conditions.”

Germany’s Angelique Kerber, a singles silver-medallist in Rio de Janeiro, will retire after the Olympics but moved in sight of a spectacular final chapter to her career as she beat Canada’s Leylah Fernandez 6-4 6-3 to reach the quarter-finals. There was better news for Canada though with Felix Auger-Aliassime thrashing Maximilian Marterer 6-0 6-1 to reach the third round of the singles.